How-to Video: PID Loop Control for A-B PLC Systems

Functions like temperature conversion, analog scaling, ramping—and even PID loop control—are done in the I/O processor instead of the PLC.

If you need to do PID loop control, you'll want to watch our latest video. Engineer Alexi Beck Gray demonstrates how to set up PID loops in SNAP I/O, change the setpoint in RSLogix, and then tune your PID loop easily in the graphical tuning tool.

While you're there, take a look at the first three IO4AB videos, too. SNAP I/O makes it easier to expand your A-B PLC system and add process control features without increasing scan times or straining the system.

New 32-Channel Digital Input with Positive Common Connections

Here's a high-density digital (HDD) module with a negative input and positive common connections.

With an input range of -10 to -32 VDC, the new SNAP-IDC-32N is ideal for NPN or sinking-type inputs.

Providing 32 digital input channels in one compact SNAP module, the SNAP-IDC-32N is great for OEMs and others who have applications with high point counts. It also solves space problems if you need a lot of digital input channels on one SNAP PAC rack.

Tech Tip: Offsite Testing Made Easy

Ever worked on your PAC Control strategy or PAC Display HMI project someplace away from your controllers—maybe even at home on a weekend?

Here's a tip from Pre-sales Engineer Ben Orchard on the easiest way to do it—with PAC Terminal.

PAC Terminal is a small but mighty utility program that's installed with the PAC Project software suite or its components, such as PAC Control. PAC Terminal is easy to overlook, but it's a handy tool for working offsite, especially if you have multiple controllers to test.

Here's the key: Both PAC Control and PAC Display operate based on your controller's name, not its IP address.

That means you can change, run, and test your strategy or project without having the controller on hand. All you need is PAC Terminal and SNAP PAC Sim, free software that runs on a PC and simulates a SNAP PAC controller.

For each controller you're testing, right-click its name in the list, choose Modify, and change its IP to 127.0.0.1 (the loopback address). Using the loopback address means your PC will look for a control engine internally rather than looking for an external controller. In PAC Terminal, it's easy to go down the list and change all the controllers you need to test.

Make your changes in PAC Control or PAC Display. Choose the name of the controller you want to test as the active controller. In PAC Control, disable the I/O units to avoid errors (SNAP PAC Sim simulates the controller, but not I/O.)

Launch SNAP PAC Sim. If Windows blocks some features of the program, unblock them. SNAP PAC Sim will simulate the controller.

To test on a different controller, just choose its name to make it the active one.

NOTES on SNAP PAC Sim: You can only test one controller at a time (only one instance of the simulator can be open). SNAP PAC Sim will run for 12 hours before it expires. After that you have to start it again.